Radical Engine Redesign Would Reduce Pollution, Oil Consumption

[roninblade]

In today's internal combustion engines, the pistons turn a crankshaft, which is linked to a camshaft that opens and closes the valves, directing the flow of air and exhaust into and out of the cylinders. The new method would eliminate the mechanism linking the crankshaft to the camshaft, providing an independent control system for the valves.

Because the valves' timing would no longer be restricted by the pistons' movement, they could be more finely tuned to allow more efficient combustion of diesel, gasoline and alternative fuels, such as ethanol and biodiesel, Shaver said.

The concept, known as variable valve actuation, would enable significant improvements in conventional gasoline and diesel engines used in cars and trucks and for applications such as generators, he said. The technique also enables the introduction of an advanced method called homogeneous charge compression ignition, or HCCI, which would allow the United States to drastically reduce its dependence on foreign oil and the production of harmful exhaust emissions.

The homogeneous charge compression ignition technique would make it possible to improve the efficiency of gasoline engines by 15 percent to 20 percent, making them as efficient as diesel engines while nearly eliminating smog-generating nitrogen oxides, Shaver said.

This improved combustion efficiency also would reduce emission of two other harmful gases contained in exhaust: global-warming carbon dioxide and unburned hydrocarbons. The method allows for the more precise control of the fuel-air mixture and combustion inside each cylinder, eliminating "fuel rich" pockets seen in conventional diesel engines, resulting in little or no emission of pollutants called particulates, a common environmental drawback of diesels.

The variable valve actuation system makes it possible to "reinduct," or reroute a portion of the exhaust back into the cylinders to improve combustion efficiency and reduce emissions. The system also makes it possible to alter the amount of compression in the cylinders of both conventional and HCCI engines and to adjust the mixing and combustion timing, allowing for more efficient combustion.

complete article at Science Daily

[mazdamazda]

Errr... from what I've read... this is already old-stuff already. That's just plain variable valve timing & exhaust gas recirculation - technologies that are already mainstream.

For example, that's already being used by BMW in their engines c/o Double VANOS + Valvetronic wherein the valve timing & lift is controlled electronically. Double VANOS also recirculates exhaust gas back to the intake manifold.

So what's new with their so called "radical engine redesign"?

[DacoTyan]

They're proposing valve actuations by other means rather than using a camshaft, probably along the lines of linear or pneumatic actuators.

Mixing hot exhaust with incoming fuel/air mixture reminds me of Smokey Yunick's engine concept. Yunick was a driver, mechanic, designer and who know's what else in the early years of NASCAR. He was also a contirbutor to Popular Science, where I 'found' him. If I remember correctly, his engine also uses rotary valves and runs hotter than 'normal' engines. But I think it still used spark plugs.

[mazdamazda]

They're proposing valve actuations by other means rather than using a camshaft, probably along the lines of linear or pneumatic actuators.

Hmmm, let me rephrase.

That technology is already commercially available. Heck, a camless prototype engine was already compeleted by BMW years ago utilizing electronic valve control.

Though the current problem is the cost of implementing this vis-a-vis the very reliable (and relatively cheap) camshaft technology that is currenly propelling all of our vehicles. As I've said, the variable valve timing technology is sort of a middle-ground between the two technologies.